System for converting sound waves into electrical waves



Nov. 6, 1928. f 1,690,255

H. c. sNooK- SYSTEMy FIOR CONVERTNG SOUND WAVES INTO ELECTRICAL WAVES Original Filed Sept. 22. 1922 2 Sheets-Sheet 1 mv. e, 192s.l 1,690,255

H. C. SNOKV SYSTEMFOR CONVERTING SOUND WAVES INTO ELECTRICAL WAVES original Filed sept. 22. 1922 ,2 sheets-sheer 2 Ahnn #5, 'C c IC: It.. IC l Paieiiied Nov. 6,1928.

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' nonna oLYnE sNoo-K, or'sourH oBANGE,-NEW JERSEY, "AssmNon 'ro WESTERN ELECTRIC COMPANY, INCORPORATED, YORK, vN. Y., ACOBYQRATION 0F y NEW Yom; y

vsra'riint ron coNvEn'rrNG scorn', wAvEsA in'ro ELEorR'IAL wvEs.'

original appiieaiien inea septeiiiberza '19242, ,seria1,ito5ss,s13. Divided and this" application ined 4 September 23, 1924.

' Thisfinv'ention rela-testol methods of and means for the distortionless yconversion of` sound waves intoelectrical waves.' i T This application is a division of copending i application No. 589,813, filed Septemberk 22,

1922, by H. C. Snook, y 1

Anv object of the invention is to -provlde means whereby sound waves maybe converted into electric waves. .A feature of this invention is the provision of means whereby electric `waves so formed may be employed for modulating ahigh frequency carrier wave for'transmission to distant points.

. 'A further feature of the .invention resides in an arrangement whereby sound waves may be used to control an ionized body of gas to produce electrical variati Y quency which may be used to modulate a cari rier wave.

AA further feature is the substitution of a volume of ionized air in place of a magnetic membrane to be acted upon` by sound. waves' i produced in the surrounding atmosphere. y

I In such a converting arrangement it is necessary'to operate 'a thermionieally active conductorfin anunevacua'ted space.' Hence, the `invention hasy for a furthervobject the provision of means whereby such an `ionic emitter may be maintained electrically active in the open atmosphere or inasuitable space en' closed by a plastic membrane and lilledwith a suitable gas. LThe invention is more partcularly described in connection with the accompanying drawings, wherein Fig.l 1 is a converting system whereby sound waves occurring in the atmosphere may be-converted into electrical waves and caused to modulate a carrier wave. Figs. 2, 3, 4, 5, 6, 7, and 8 are sound `convertingl arrangements kalterna- 40 ktive to that disclosed in Fig. 1. Fig. 9 illustrates an arrangement in which the converter is surrounded by a suitable gas. y

Referring-more particularly to Fig. 1 a- `filament 1 is heated by a battery 2 or other suitable means and caused to become electronically activel Adjacent to and opposite the filament is an anode 3 having an external connection to the filament through ay battery 4 havin a suitable terminal electromotive force. n electromagnet 5 of suitable field strength is located with its poles longitudivnally arranged with respect to the ,axes consemiv no. 739,330.

necting the filament land the anode' 3. Elec# trodes 6 are connected to the terminals of transformer 47 which is. connected to the inputcircuit of amplifier 10.. A battery '31I supplies the circuitof electrodes 6 with suitl able energy."V The outputv of amplifier 10 is connected vto the primary of transformer 9 for impressing waves upon ,a carrier line 11 for modulation thereof. VThe ionized stream' v flowing between electrodes '1 and 3 may be acted upon Vby speech vor other soundwaves as shown at 12 Fg, 2; A wave variation of sound frequency results in the speech frequency circuit oftwhch electrodes 6 and the primary winding of transformer 7 v`form a part. It is readily seen then that this aronsof audible fre-"rangement constitutes what may be recognized as amicrophone. The alternate condensation and'rarefaction of the atmospheric 4 space occupied by the ionized stream due to the lncomlng sound waves changes the impedance of circuit 6-31--7 with consequent 'changes in the current flowing therein.

j In Fig. 2 the sound waves assh'own by the arrows at 12, act upon the ionized stream 'between electrodes 1 and 3 to vary the imedance'ofthe associated circuit in which are included the primary of transformer 13, battery 14 and regulating-resistance 15. The waves are then transmitted over line 16 to any distant point where, after amplification by means of amplier'l?, theymay be reproduced in loud speaker 18 or by any other Well known means.

The arrangement ofV Fig. 3 differs from Fig. 2 in that the anode 3 is in the form of a hemisplierical wire` basket thus vPermitting sounds existing in the neighborhood of the device toreach the ionized stream.' In order to assist the sound waves a conical protector 20 having hard deflecting walls of insulating material partially surrounds the space occupiedby the stream.A With this device sound waves directed toward the stream will be concentrated because of the reflection caused by the protector 20.

In the arrangement of Fig. 4 filament 1`- and anode 3 are arranged in'a manner similar. to that of Fig. 1. However, one of the speech output electrodes corresponding to the electrode 6 of Fig. 1 is arranged in the center portion as indicated at 21 and has an insulated lead-in connection 22. The other electrode is in the form of a hollow spherical conducting cage 23 which has the remaining electrodes contained within itself and has the electrode 21 at the geometrical center. lVith this apparatus it is not necessary that the sound waves be directed toward the stream but any sound occurring within the room in Vwhich the apparatus is located may have easy access to the ionized stream.

In Fig. 5 serv-al electron emitting filaments 1 arranged in the form of a frustum of a cone are associated with the anode 3. The speech output electromotive force is applied to the electrodes 21 and Q3, the latter of which is in the form of a hemispheri'cal metal cage or ln1slet,similarin form to the anode of Fig. 3 and is associated with a hard sound reflecting cone 2O as in Fig. 3. The filaments are preferablyv mounted on cone 20.

In Fig. (3 the output circuit for the wave representing the sound to be converted into electrical energy is directly in series with the cathode, anode circuit 1, 4, 3 as in the case of Fig. 2 but a` transverse magnetic field is superimposed upon the region which the ions traverse in traveling from the cathode 1 to the yanode 3. This magnetic field provided with a suitably energized electromagnet 5.

In Fig. 7 the output circuit for the waves controlled by the ionic stream is superimposed upon the uni-directional current circuit of the electromagnet In this` case, transformer 19 is the output transformer. A constant transverse electromagnetic field is thus provided upon which is superiml'iosed electromagnetic variations resulting from the variations in the ionic stream, due to Contact with sound waves to he converted.

Fig. 8 differs from Fig. 6 in that a longitudinal magnetic field is produced by the elcctromagnet 5, that is to say, the magnetic lines of force are in general parallel to the paths taken by ions traveling between the cathode 1 and anode 3.

Fig. 9 illustrates an arrangement for enclosing the electron emitting filament and its associated anode, if desired, in a plastic wall membrane within which is contained suitable gases such as nitrogen, hydrogen, argon or a suitable mixturepof these or other gases. Itis particularly desirable to exclude gases which exercise a so-called poisoning action upon certain common used forms of thermionic electron` emitters, such asplatinum, tungsten or alkaline-earth, oxide-coated platinum wires. Furthermore, as has been published by Mr; O. lV. Richardson and others, the presence of gaseous hydrogen, even in minute quantities, greatly increases the thermionic emission'from such electron emitters. In Fig. 9, cathode 1 and anode 3 are surrounded by aA thin rubber membrane 30 resenibling a toy balloon or some other equivalent air-tight membrane. The gas may be supplied through an inputl pipe Q8 and led otl through an output pipe Q9 each of which may be provided with suitable stop cocks or other means for regulating the flow. In particular it is contemplated to supply gaseous hydrogen and some other inert gas such as nitrogen. This mixture may be very conveniently produced by .supplying to the space surrounding the electrodes gaseous ammonia which upon being disassociatcd by the electric discharge will break down into gaseous hydrogen and gaseous nitrogen. Consequently, there results inerascd cinission ot negative electrons :from the electron emitter andan elimination of the'so called poisoning action of gaseous oxygen. This arrangement for surrounding an electron emitter with some inert or other gas or a mixture of gases and excluding ordinary atmosphere is applicable to arrangements such as shown in Figs. 1 to 8, and other modifications not illustrated as well as Fig. 9. The. electrode arrangement and input sup ply of Fig. 9 is generally similar to that of Fig. 2..

Reference will nowl be made to the operation of the sound converter of Fig. 1. It is contemplated that the region between and `surrouiuling thc electrodes 1 and Il should consist of ionized air butI this ionized space will not have such a high degree of ionization that it possesses the appearance and characteristics which are recognized as characteristic of'a Voltaic are. On the contrary it is contemplated that this space shall have within it ionized carriers which are fewer per unit volume within this space than the density of such carriers within the ionized stream oi' a so-called Voltaic arc. It is proposed to use1ionized spaces in open atmosliheric air and operates upon them by directing the sound waves thereat so as tobe able to transfer energy from the non-ionized atmospheric air in the vicinity without the agency of a diaphragm of solid material possessing me chanical mass of any appreciable amount. In order to transfer energy directly from the at- .mosphcre, it is contel'nplatcd to influence the charged electrical carriers thus produced in an ionized space'. These small particles ionized molecules or ions or charged molecular aggregates, are the means tortransferring to electrical circuits the energy of the molecules oit the non-ionized atmospheric air, that is, in the form of heat or sounds, by causing the ionized particles to collide with the nonionized molecules in the air. The ionized spaces which are used may be ionized not only by the means hereinbeforc described but by the use of such known methods as flames burning in open air, intenselbemns of X-rays 'through a space in atmospheric air, by the transmission of radiations 'from a radioactive substance through a space in atmoslll) lun

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pheric air or by thetransmission of ultraviolet or other kinds of light througha space in Vatmospheric air or bythe' use of incandescent electron emitting bodies other 'than those described. Such electron 'emitting bodies may be incandescent metals coated with: oxides of the alkaline earths vor other substances, incandescent oxides of thorium7 or other electron emitter; V

In such arrangements as F ig. 1 theele'ments 6 constitute electrodes immersed. withinl or adjacent .to the ionized space. They are so arranged as to collect more or less of the large ions and thus transfer electrical variations to t output circuit. -By being in Contact with the non-ionized adjacent air sound vibrations existing in the adjacent air modify the im'- pedance in the space between the elements 6. In accordance with this method ofthe vari ation of impedance in the ionized space, it is `not necessary that the lions of one kind o'l' sign predominate in number overr those of the opposite kind of sign providing the-den*- sity of the carriers in the ionized space is low enough to permit the electric lield fromthe electrodes 6^, energized the battery 31', to penetrate appreciably into the ionized space.

That is to say',- the density ofthe carriers of one kind of sign must not be great enough to shield the electric eld from the carriers of the opposite sign. n Onthe'other hand, if the carriers. of one kind of sign predominate, it is easily -seen that the carriers may be deflected vby the electric eld between the control electrodes. In Fig. 1 the magnetic field may be transverse vas in Fig. G, if desired.

The arrangements ofFig's. 2, 3, 6 and 8 are illustrative of a method of variation orv impedance between. additional electrodes,v

provided they are supplied, and the bulk of the carriers between the anode and the cathode in each said instance are charged ionic carriers of one kind of sign of molecular magnitude. One method of accomplishing this predominance of charged carriers of one kind of sign of molecular magnitude is have the electron emitting element 1 not emit negative electronsbut instead to make it an" emitter lof positive ions and to have these positive ions traverse the space between the cathode and anode, which' are maintained at a given potential, such that at no time in their VHight across this space will these positively charged carriers ofA molecular magnitude have acquired a velocity s uiiicient to ioniae the air within the space. inotherinethod oi accomplishing the predominance o-E charged carriers oiE one kind of sign ot molecularmagnitude is to maintain a potential gradient in the space between the negative eiectron emitter 1 and its cooper-l ating anode so small that the electrons do not,'

on the average; attain suiicient velocity to ionize the air molecules in the space. The

negative electrons then attach themselves to some` of the uncharged air molecules. land* heavy negative ions and molecular aggregates are thus obtained. lThe density. of the charged carriers within the ionized space isl not great enough so that the carriers of one kind of sign, either positive or negative, exercise a strong orlarge shielding action lupon the carriers or the other kind of sign. In the case o electric arcs there is an approximately volume for which vreasonrelatively low densities oi ionization are made use of in lthe present instance, as hereinbefore stated. j In the arrangement of Fig'.4 6 the magnetic eld is transverse to the ionized field and the space between the output electrodes.' The` audible variation inthe non-ionized air in the vicinity oi the cathode and anode bring about audio frequency variations of the ionizing current. There is thus provided a means of varying the energy in theV space in the vicinity of the cathode and anode, l and 3 in synchronism with the audible sounds to be convertedi Inlig. 7 -theionization current is transverse to the .audio frequency magnetic field.

Sound vibrations occurring in the non-ionized air cause the sheet of ionized air which `is steadily ionized by'a steady direct current ,to be'moved back and forthcausing pulsations of flux across the space 'between the poles of the magnet. The sheet of ionized air occupies the bulk of space between the 1 poles ofthe magnet which causes the variations of currents to occur in the output circuit corresponding to and constituting the undistorted speech waves.

In Fig. 8 the ionization current is located in a longitudinal magnetic iield. The motion of the charged carriers will be in the form of lelices or spirals around the line of magnetic It is possible in connection with the preceding arrangement to make use of electrostatic or electromotive fields which are oblique with respect to each other or to the ionization field or both. 4ln this case they will have both the transverse and the longitudinal components.

The disclosures herein are schematic and are not intended to indicate dimensions either velectrically or mechanically. The general dimensions will be known to-those skilled in the art'from a study of experimental data already published in-the general literature cf llU MSU

ionization and the necessary dimensions for producing the best results in any individual case are necessarily determined by adjusting the apparatus to obtain the maximum results.

Having described various methods, systems, apparatus, and elements cooperating to produce a.sound converting system, the novel features believed to be inherent in the inventionA` are set forth in the appended claims.

What is claimed is:

1. An arrangement for converting sound into electrical changes which comprises means for establishing an ionized field in a bodjv of gas exposed to variations in pressure .due to sound, means for superimposing thereon a steady electromagneticfield and means for producing an electrostatic fieldl in'said bodj,7 of gas. Y

2. The method ot producing electrical changes in a circuit which consists in producing an ionized path in said circuit, applying an electrostatic field transverse said path, and a steady magnetic field longitudinal of said path and exposing said path directly to sound Waves.

3. In a device for the translation ot sound into electrical changes, a cathode and an anode in spaced relation, the space therebetween beingr exposed to pressure vibrations due directly to sound Without the cooperating of any movable mass, means for subjecting said s ace to an electrostatic field, and means for su jecting said space'to a steady magnetic -on the other side,

5. In a device for translating sound into electrical changes, a cathode, an anode, means tor producing a potential difference between lsaid electrodes, the space between said electrodes being open to the atmosphere whereby it is subjected to pressure vibrations div, to sound and said potential difference being at all times too small to produce substantial ionization ofthe atmosphere in said space`v and a pair of concentric electrodes for subjecting said space to a static potential, the outer of' said concentric electrodes consisting of a conducting cage through which the sound waves may freely pass to the space between the anode and 'athode In Witness whereof, I hereunto subscribe vmy name this 22nd day of September A. D.,

H..CLYDE SNOGK. 

